2161264661 has 4 divisors (see below), whose sum is σ = 2175577824. Its totient is φ = 2146951500.

The previous prime is 2161264657. The next prime is 2161264681. The reversal of 2161264661 is 1664621612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2161264661 - 2² = 2161264657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161264601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7156355 + ... + 7156656.

It is an arithmetic number, because the mean of its divisors is an integer number (543894456).

Almost surely, 2^2161264661 is an apocalyptic number.

It is an amenable number.

2161264661 is a deficient number, since it is larger than the sum of its proper divisors (14313163).

2161264661 is a wasteful number, since it uses less digits than its factorization.

2161264661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14313162.

The product of its digits is 20736, while the sum is 35.

The square root of 2161264661 is about 46489.4037496718. The cubic root of 2161264661 is about 1292.9130453111.

The spelling of 2161264661 in words is "two billion, one hundred sixty-one million, two hundred sixty-four thousand, six hundred sixty-one".